JP2008-127200A proposes a lateral movement mechanism on an overhead travelling vehicle to laterally move an elevation device that lifts and lowers articles. The lateral movement mechanism is configured of, for example, a belt-driven slide fork, and if the belt is cut, a moving unit of the slide fork may unintentionally project and interfere with an overhead travelling vehicle opposite thereto or, for example, a strut of a buffer in the neighborhood thereof.
There is a need in the art to prevent a moving unit from unintentionally projecting even when trouble has occurred with a lateral movement mechanism.